A rotor consists of four horizontal blades each of length L = 4 m and mass m = 90 kg cantilevered off of a vertical shaft. Assume that each blade can be modeled as having its mass concentrated at its midpoint. The rotor is initially at rest when it is subjected to a moment M = βt, with β = 60 N·m/s. Determine the angular speed of the rotor after 10s.